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/*-
* ============LICENSE_START=======================================================
* Copyright (C) 2016-2018 Ericsson. All rights reserved.
* ================================================================================
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* SPDX-License-Identifier: Apache-2.0
* ============LICENSE_END=========================================================
*/
package org.onap.policy.apex.service.engine.event.impl.jsonprotocolplugin;
import java.util.ArrayList;
import java.util.List;
import org.onap.policy.apex.context.SchemaHelper;
import org.onap.policy.apex.context.impl.schema.SchemaHelperFactory;
import org.onap.policy.apex.model.basicmodel.service.ModelService;
import org.onap.policy.apex.model.eventmodel.concepts.AxEvent;
import org.onap.policy.apex.model.eventmodel.concepts.AxEvents;
import org.onap.policy.apex.model.eventmodel.concepts.AxField;
import org.onap.policy.apex.service.engine.event.ApexEvent;
import org.onap.policy.apex.service.engine.event.ApexEventException;
import org.onap.policy.apex.service.engine.event.ApexEventProtocolConverter;
import org.onap.policy.apex.service.engine.event.ApexEventRuntimeException;
import org.onap.policy.apex.service.parameters.eventprotocol.EventProtocolParameters;
import org.slf4j.ext.XLogger;
import org.slf4j.ext.XLoggerFactory;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
/**
* The Class Apex2JSONEventConverter converts {@link ApexEvent} instances to and from JSON string representations of
* Apex events.
*
* @author Liam Fallon (liam.fallon@ericsson.com)
*/
public class Apex2JSONEventConverter implements ApexEventProtocolConverter {
private static final XLogger LOGGER = XLoggerFactory.getXLogger(Apex2JSONEventConverter.class);
// The parameters for the JSON event protocol
private JSONEventProtocolParameters jsonPars;
/*
* (non-Javadoc)
*
* @see org.onap.policy.apex.service.engine.event.ApexEventProtocolConverter#init(org.onap.policy.
* apex.service.parameters.eventprotocol.EventProtocolParameters)
*/
@Override
public void init(final EventProtocolParameters parameters) {
// Check and get the JSON parameters
if (!(parameters instanceof JSONEventProtocolParameters)) {
final String errorMessage = "specified consumer properties are not applicable to the JSON event protocol";
LOGGER.warn(errorMessage);
throw new ApexEventRuntimeException(errorMessage);
}
jsonPars = (JSONEventProtocolParameters) parameters;
}
/*
* (non-Javadoc)
*
* @see org.onap.policy.apex.service.engine.event.ApexEventConverter#toApexEvent(java.lang.String, java.lang.Object)
*/
@Override
public List<ApexEvent> toApexEvent(final String eventName, final Object eventObject) throws ApexEventException {
// Check the event eventObject
if (eventObject == null) {
LOGGER.warn("event processing failed, event is null");
throw new ApexEventException("event processing failed, event is null");
}
// Cast the event to a string, if our conversion is correctly configured, this cast should
// always work
String jsonEventString = null;
try {
jsonEventString = (String) eventObject;
} catch (final Exception e) {
final String errorMessage = "error converting event \"" + eventObject + "\" to a string";
LOGGER.debug(errorMessage, e);
throw new ApexEventRuntimeException(errorMessage, e);
}
// The list of events we will return
final List<ApexEvent> eventList = new ArrayList<>();
try {
// We may have a single JSON object with a single event or an array of JSON objects
final Object decodedJsonObject = new GsonBuilder().serializeNulls().create().fromJson(jsonEventString,
Object.class);
// Check if we have a list of objects
if (decodedJsonObject instanceof List) {
// Check if it's a list of JSON objects or a list of strings
@SuppressWarnings("unchecked")
final List<Object> decodedJsonList = (List<Object>) decodedJsonObject;
// Decode each of the list elements in sequence
for (final Object jsonListObject : decodedJsonList) {
if (jsonListObject instanceof String) {
eventList.add(jsonStringApexEvent(eventName, (String) jsonListObject));
} else if (jsonListObject instanceof JsonObject) {
eventList.add(jsonObject2ApexEvent(eventName, (JsonObject) jsonListObject));
} else {
throw new ApexEventException("incoming event (" + jsonEventString
+ ") is a JSON object array containing an invalid object " + jsonListObject);
}
}
} else {
eventList.add(jsonStringApexEvent(eventName, jsonEventString));
}
} catch (final Exception e) {
final String errorString = "Failed to unmarshal JSON event: " + e.getMessage() + ", event="
+ jsonEventString;
LOGGER.warn(errorString, e);
throw new ApexEventException(errorString, e);
}
// Return the list of events we have unmarshalled
return eventList;
}
/*
* (non-Javadoc)
*
* @see org.onap.policy.apex.service.engine.event.ApexEventConverter#fromApexEvent(org.onap.policy.
* apex.service.engine.event.ApexEvent)
*/
@Override
public Object fromApexEvent(final ApexEvent apexEvent) throws ApexEventException {
// Check the Apex event
if (apexEvent == null) {
LOGGER.warn("event processing failed, Apex event is null");
throw new ApexEventException("event processing failed, Apex event is null");
}
// Get the event definition for the event from the model service
final AxEvent eventDefinition = ModelService.getModel(AxEvents.class).get(apexEvent.getName(),
apexEvent.getVersion());
// Use a GSON Json object to marshal the Apex event to JSON
final Gson gson = new GsonBuilder().serializeNulls().setPrettyPrinting().create();
final JsonObject jsonObject = new JsonObject();
jsonObject.addProperty(ApexEvent.NAME_HEADER_FIELD, apexEvent.getName());
jsonObject.addProperty(ApexEvent.VERSION_HEADER_FIELD, apexEvent.getVersion());
jsonObject.addProperty(ApexEvent.NAMESPACE_HEADER_FIELD, apexEvent.getNameSpace());
jsonObject.addProperty(ApexEvent.SOURCE_HEADER_FIELD, apexEvent.getSource());
jsonObject.addProperty(ApexEvent.TARGET_HEADER_FIELD, apexEvent.getTarget());
if (apexEvent.getExceptionMessage() != null) {
jsonObject.addProperty(ApexEvent.EXCEPTION_MESSAGE_HEADER_FIELD, apexEvent.getExceptionMessage());
}
for (final AxField eventField : eventDefinition.getFields()) {
final String fieldName = eventField.getKey().getLocalName();
if (!apexEvent.containsKey(fieldName)) {
if (!eventField.getOptional()) {
final String errorMessage = "error parsing " + eventDefinition.getID() + " event to Json. "
+ "Field \"" + fieldName + "\" is missing, but is mandatory. Fields: " + apexEvent;
LOGGER.debug(errorMessage);
throw new ApexEventRuntimeException(errorMessage);
}
continue;
}
final Object fieldValue = apexEvent.get(fieldName);
// Get the schema helper
final SchemaHelper fieldSchemaHelper = new SchemaHelperFactory().createSchemaHelper(eventField.getKey(),
eventField.getSchema());
jsonObject.add(fieldName, (JsonElement)fieldSchemaHelper.marshal2Object(fieldValue));
}
// Output JSON string in a pretty format
return gson.toJson(jsonObject);
}
/**
* This method converts a JSON object into an Apex event.
*
* @param eventName
* the name of the event
* @param jsonEventString
* the JSON string that holds the event
* @return the apex event that we have converted the JSON object into
* @throws ApexEventException
* thrown on unmarshaling exceptions
*/
private ApexEvent jsonStringApexEvent(final String eventName, final String jsonEventString)
throws ApexEventException {
// Use GSON to read the event string
final JsonObject jsonObject = new GsonBuilder().serializeNulls().create().fromJson(jsonEventString,
JsonObject.class);
if (jsonObject == null || !jsonObject.isJsonObject()) {
throw new ApexEventException(
"incoming event (" + jsonEventString + ") is not a JSON object or an JSON object array");
}
return jsonObject2ApexEvent(eventName, jsonObject);
}
/**
* This method converts a JSON object into an Apex event.
*
* @param eventName
* the name of the event
* @param jsonObject
* the JSON object that holds the event
* @return the apex event that we have converted the JSON object into
* @throws ApexEventException
* thrown on unmarshaling exceptions
*/
private ApexEvent jsonObject2ApexEvent(final String eventName, final JsonObject jsonObject)
throws ApexEventException {
// Process the mandatory Apex header
final ApexEvent apexEvent = processApexEventHeader(eventName, jsonObject);
// Get the event definition for the event from the model service
final AxEvent eventDefinition = ModelService.getModel(AxEvents.class).get(apexEvent.getName(),
apexEvent.getVersion());
// Iterate over the input fields in the event
for (final AxField eventField : eventDefinition.getFields()) {
final String fieldName = eventField.getKey().getLocalName();
if (!hasJSONField(jsonObject, fieldName)) {
if (!eventField.getOptional()) {
final String errorMessage = "error parsing " + eventDefinition.getID() + " event from Json. "
+ "Field \"" + fieldName + "\" is missing, but is mandatory.";
LOGGER.debug(errorMessage);
throw new ApexEventException(errorMessage);
}
continue;
}
final JsonElement fieldValue = getJSONField(jsonObject, fieldName, null, !eventField.getOptional());
if (fieldValue != null && !fieldValue.isJsonNull()) {
// Get the schema helper
final SchemaHelper fieldSchemaHelper = new SchemaHelperFactory().createSchemaHelper(eventField.getKey(),
eventField.getSchema());
apexEvent.put(fieldName, fieldSchemaHelper.createNewInstance(fieldValue));
} else {
apexEvent.put(fieldName, null);
}
}
return apexEvent;
}
/**
* This method processes the event header of an Apex event.
*
* @param eventName
* the name of the event
* @param jsonObject
* the JSON object containing the JSON representation of the incoming event
* @return an apex event constructed using the header fields of the event
* @throws ApexEventRuntimeException
* the apex event runtime exception
* @throws ApexEventException
* on invalid events with missing header fields
*/
private ApexEvent processApexEventHeader(final String eventName, final JsonObject jsonObject)
throws ApexEventException {
// Get the event header fields
// @formatter:off
String name = getJSONStringField(jsonObject, ApexEvent.NAME_HEADER_FIELD, jsonPars.getNameAlias(), ApexEvent.NAME_REGEXP, false);
String version = getJSONStringField(jsonObject, ApexEvent.VERSION_HEADER_FIELD, jsonPars.getVersionAlias(), ApexEvent.VERSION_REGEXP, false);
String namespace = getJSONStringField(jsonObject, ApexEvent.NAMESPACE_HEADER_FIELD, jsonPars.getNameSpaceAlias(), ApexEvent.NAMESPACE_REGEXP, false);
String source = getJSONStringField(jsonObject, ApexEvent.SOURCE_HEADER_FIELD, jsonPars.getSourceAlias(), ApexEvent.SOURCE_REGEXP, false);
String target = getJSONStringField(jsonObject, ApexEvent.TARGET_HEADER_FIELD, jsonPars.getTargetAlias(), ApexEvent.TARGET_REGEXP, false);
// @formatter:on
// Check that an event name has been specified
if (name == null && eventName == null) {
throw new ApexEventRuntimeException(
"event received without mandatory parameter \"name\" on configuration or on event");
}
// Check if an event name was specified on the event parameters
if (eventName != null) {
if (name != null && !eventName.equals(name)) {
LOGGER.warn("The incoming event name \"{}\" does not match the configured event name \"{}\", using configured event name",
name, eventName);
}
name = eventName;
}
// Now, find the event definition in the model service. If version is null, the newest event
// definition in the model service is used
final AxEvent eventDefinition = ModelService.getModel(AxEvents.class).get(name, version);
if (eventDefinition == null) {
throw new ApexEventRuntimeException("an event definition for an event named \"" + name
+ "\" with version \"" + version + "\" not found in Apex model");
}
// Use the defined event version if no version is specified on the incoming fields
if (version == null) {
version = eventDefinition.getKey().getVersion();
}
// Check the name space is OK if it is defined, if not, use the name space from the model
if (namespace != null) {
if (!namespace.equals(eventDefinition.getNameSpace())) {
throw new ApexEventRuntimeException("namespace \"" + namespace + "\" on event \"" + name
+ "\" does not match namespace \"" + eventDefinition.getNameSpace()
+ "\" for that event in the Apex model");
}
} else {
namespace = eventDefinition.getNameSpace();
}
// For source, use the defined source only if the source is not found on the incoming event
if (source == null) {
source = eventDefinition.getSource();
}
// For target, use the defined source only if the source is not found on the incoming event
if (target == null) {
target = eventDefinition.getTarget();
}
return new ApexEvent(name, version, namespace, source, target);
}
/**
* This method gets an event string field from a JSON object.
*
* @param jsonObject
* the JSON object containing the JSON representation of the incoming event
* @param fieldName
* the field name to find in the event
* @param fieldAlias
* the alias for the field to find in the event, overrides the field name if it is not null
* @param fieldRE
* the regular expression to check the field against for validity
* @param mandatory
* true if the field is mandatory
* @return the value of the field in the JSON object or null if the field is optional
* @throws ApexEventRuntimeException
* the apex event runtime exception
*/
private String getJSONStringField(final JsonObject jsonObject, final String fieldName, final String fieldAlias,
final String fieldRE, final boolean mandatory) {
// Get the JSON field for the string field
final JsonElement jsonField = getJSONField(jsonObject, fieldName, fieldAlias, mandatory);
// Null strings are allowed
if (jsonField == null || jsonField.isJsonNull()) {
return null;
}
// Check if this is a string field
String fieldValueString = null;
try {
fieldValueString = jsonField.getAsString();
} catch (final Exception e) {
// The element is not a string so throw an error
throw new ApexEventRuntimeException("field \"" + fieldName + "\" with type \""
+ jsonField.getClass().getCanonicalName() + "\" is not a string value");
}
// Is regular expression checking required
if (fieldRE == null) {
return fieldValueString;
}
// Check the event field against its regular expression
if (!fieldValueString.matches(fieldRE)) {
throw new ApexEventRuntimeException(
"field \"" + fieldName + "\" with value \"" + fieldValueString + "\" is invalid");
}
return fieldValueString;
}
/**
* This method gets an event field from a JSON object.
*
* @param jsonObject
* the JSON object containing the JSON representation of the incoming event
* @param fieldName
* the field name to find in the event
* @param fieldAlias
* the alias for the field to find in the event, overrides the field name if it is not null
* @param mandatory
* true if the field is mandatory
* @return the value of the field in the JSON object or null if the field is optional
* @throws ApexEventRuntimeException
* the apex event runtime exception
*/
private JsonElement getJSONField(final JsonObject jsonObject, final String fieldName, final String fieldAlias,
final boolean mandatory) {
// Check if we should use the alias for this field
String fieldToFind = fieldName;
if (fieldAlias != null) {
fieldToFind = fieldAlias;
}
// Get the event field
final JsonElement eventElement = jsonObject.get(fieldToFind);
if (eventElement == null) {
if (!mandatory) {
return null;
} else {
throw new ApexEventRuntimeException("mandatory field \"" + fieldToFind + "\" is missing");
}
}
return eventElement;
}
/**
* This method if a JSON object has a named field.
*
* @param jsonObject
* the JSON object containing the JSON representation of the incoming event
* @param fieldName
* the field name to find in the event
* @return true if the field is present
* @throws ApexEventRuntimeException
* the apex event runtime exception
*/
private boolean hasJSONField(final JsonObject jsonObject, final String fieldName) {
// check for the field
return jsonObject.has(fieldName);
}
}
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